Support for overlay only files in Analysis Server with the new driver.

pkg/analysis_server/lib/src/analysis_server.dart

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library analysis.server;
 
 import 'dart:async';
 import 'dart:collection';
 import 'dart:core';
 import 'dart:io' as io;
@@ skipping 1469 matching lines @@
         } else {
           // Protocol parsing should have ensured that we never get here.
           throw new AnalysisException('Illegal change type');
         }
 
         fileContentOverlay[file] = newContents;
 
         driverMap.values.forEach((driver) {
           driver.changeFile(file);
         });
+
+        // If the file did not exist, and is "overlay only", it still should be
+        // analyzed. Add it to driver to which it should have been added.
+        contextManager.getDriverFor(file)?.addFile(file);
+
         // TODO(scheglov) implement other cases
       });
       return;
     }
     changes.forEach((file, change) {
       ContextSourcePair contextSource = getContextSourcePair(file);
       Source source = contextSource.source;
       operationQueue.sourceAboutToChange(source);
       // Prepare the new contents.
       String oldContents = overlayState.getContents(source);
@@ skipping 620 matching lines @@
   /**
    * The [PerformanceTag] for time spent in server request handlers.
    */
   static PerformanceTag serverRequests = new PerformanceTag('serverRequests');
 
   /**
    * The [PerformanceTag] for time spent in split store microtasks.
    */
   static PerformanceTag splitStore = new PerformanceTag('splitStore');
 }